After the skin is excessively exposed in ultraviolet, epidermal cells are injured. Tyrosinase is activated to accelerate pigment synthesis, destroy the moisturizing function of the skin, so that the skin becomes dry, elastic fibers in the corium layer are injured, and fine lines are generated. Also the skin may be inflammatory and burnt under intensive irradiation. Pigmentary skin cancer and the like may occur under exceptional conditions. Sunshine may be accumulated, and long-term accumulation of skin injury may lead to the phenomena of skin suntan, flecks on the face, skin elasticity losing, wrinkles, ageing and the like. Long-brim hats are popular due to the advantages of being convenient for outgoing and light in wearing. However, the height of the sun is different in different seasons and at different time in a day, and the sunlight incident angle is changing all the time. For example, in the morning, the sun is low, the incident angle is small and a large area is irradiated, while at noon, the sun is high, the incident angle is large and a small area is irradiated, so a very wide hat brim is needed for all-day protection. However, a too wide hat brim may block the sight and affect outgoing and the enjoyment of scenery.